isReadOnly() now takes arguments

Add an array of arguments to isReadOnly() method of actions, to let
them change their results depending on what actions are called.
Primarily used by the 'api' action. Ideally in the future that will be
multiple actions. But this might still be useful.

lib/action.php

@@ -791,9 +791,12 @@ class Action extends HTMLOutputter // lawsuit
      *
      * MAY override
      *
+     * @param array $args other arguments
+     *
      * @return boolean is read only action?
      */
-    function isReadOnly()
+
+    function isReadOnly($args)($args)
     {
         return false;
     }